<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    const map2 = new WeakMap()

    let key2 = {}
    let obj2 = {m: 2}
    map2.set(key2, obj2)

    key2 = null
    const arr = []
    for (let index = 0; index < 100000; index++) {
      arr.push(new Array(1000))
    }
    // console.log(map.get(key1))
    setTimeout(() => {
      console.log(map2.)
    }, 7000);
  </script>
</body>
</html>